In an investigation of the Environmental Protection Administration, it is found that household (indoor) air pollution is higher than outdoor air pollution by several times to tens of times. Air pollution is likely to cause pulmonary allergy or asthma. Therefore, many families purchase air cleaners to improve the quality of indoor air.
A common air cleaner uses an electric fan to suck and exhaust air, wherein several filters are arranged before the electric fan, and wherein the blades of the electric fan are driven by a motor to rotate at a high speed to suck air into the air cleaner, whereby the particles suspended in the air is filtered out by the filters. However, the filters cannot completely filter very tiny particles suspended in the air. Therefore, a common air cleaner cannot solve but can only soothe the problem of allergy. Besides, filters need replacing frequently to maintain the highest efficiency of the air cleaner, which would raise household expenditure. Further, dirt and particles are likely to adhere to filters and blades, which may cause noise, impair air suction, and increase power consumption.
There have been air-cleaning devices using water to filter and purify air available in the market. For an example, Taiwan patent publication No. 201041642 disclosed a water-circulation air cleaning device for absorbing hydrogen sulfide. Refer to FIG. 1. The prior-art air cleaning device 1 comprises a water tank 10, a pump 11, a venturi tube 12, a side pipe 13, a guiding and filtering device 14, an ion concentration monitoring device and a timer. The pump 11 sends out water W3, and the venturi tube 12 accelerates water W3, whereby pressure drop is formed in the venturi tube 12. Next, the side pipe 13 sucks air A3 into water W3. Next, air A3 is mixed with water W3, and hydrogen sulfide is dissolved in water W3. Then, hydrogen sulfide is removed from air A3, and clean air A31 is obtained. However, the prior art has a problem: clean air A31 cannot be exhausted from the water tank 10 but is persistently accumulated in the water tank 10. Excessively accumulated clean air A31 will gradually decrease the amount of water W3 that the pump 11 can pump from the water tank 10 and finally make the venturi tube 12 unable to suck air A3. Thus, the air-water mixing and air cleaning function of the air cleaning device is disabled.
For another example, Taiwan patent No. 352007 disclosed a waste gas processing device using a venturi tube-based gas cleaning tower. Refer to FIG. 2. In the prior-art waste gas processing device 2, a pump 21 cyclically pumps an absorbing liquid W4; a venturi tube-based vacuum sucker 23 bypassed from a main pipe 22 sucks waste gas A4 to contact and mix with the absorbing liquid W4 in the gas cleaning tower, whereby the waste gas A4 is atomized into bubbles in the absorbing liquid W4. Next, a static agitation pipe 24 thoroughly mixes the liquid and the gas. Next, the mixture of gas and liquid is injected from an aeration pipe 25 in a water tank 20, whereby the dust in the waste gas A4 is captured by the absorbing liquid W4 of the gas cleaning tower and deposits in the water tank 20. Then, clean air A41 is exhausted from an exhaust pipe 26. Thus, the waste gas A4 is purified. However, there are two factors impairing household application of the prior art: only a single set of the venturi tube-based vacuum sucker 23 is hard to suck sufficient waste gas A4 for effectively purifying the waste gas A4; the absorbing liquid W4 of the gas cleaning tower needs manually replacing frequently.